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to a much larger ongoing project encompassing the entire Colorado River basin in Utah that included many additional objectives. These additional objectives are not addressed in this report. METHODS Study Area Westwater Canyon is located on the Colorado River downstream of the CO-UT border. The length of the canyon extends approximately twelve miles (RM 124.5-112.5). It is characterized by the black Proterozoic gneiss and granite complex that comprise the inner gorge. The habitat in the upper section of the canyon consists of runs, eddies, and pools interspersed between riffles and rapids. The ~ steepest part of Westwater Canyon is the middle section (RM 119.5-116.5). This portion of the canyon was not sampled due to the turbulent flows and Class III rapids. However, U.S. Fish and Wildlife Service sampled the middle section of Westwater Canyon during 1979-1981 and humpback chub were present (Valdez et al. 1982). The lower section of Westwater Canyon is a confined canyon reach with a reduced gradient that primarily comprises a homogeneous run where chubs are scarce (Chart and Lentsch 1999). Humpback chub sampling occurred at three sites in the upper portion of Westwater Canyon previously established for the Interagency Standardized Monitoring Program (ISMP): Miners Cabin (RM 124.1-123.8), Cougar Bar (RM 121.5-121.0), and Hades Bar (RM 120.0-119.8). Depth measurements collected in 1994 for each of these sites resulted in maximum depths of 21.8 m at ~ Miners Cabin, 19.5 m at Cougar Bar, and 10.6 m at Hades Bar (Chart and Lentsch 1999). Each of these deep canyon habitats is bounded by a riffle area. Sampling A Humpback chub sampling in Westwater Canyon occurred during September and October throughout the three years of the study. Three sampling passes were conducted each year. Eight days lapsed between the end of one pass and the beginning of the subsequent pass. During each pass, Miners Cabin was sampled for two nights, Cougar Bar was sampled for two nights and Hades Bar was sampled for one night. Gear included the use of trammel nets (23 m x 2 m; 2.5 cm and 1.25 cm ~ mesh) and a pulsed DC Coffelt® electrofishing unit mounted on an inflatable sport boat. Trammel nets were set in mid-afternoon and checked every two hours until midnight, at which time they were pulled. Nets were reset before dawn and allowed to fish until late morning while being checked every two hours. Trammel nets were set to target juvenile and adult chubs. Trammel nets were primarily set in deep eddies off boulders or rock faces. Nets were occasionally set in relatively ~ shallow riffle/run areas off in-channel boulders. All Gila spp. caught were removed from the net and placed in a holding pen until they were processed at the end of each 18-hour sampling period. Electrofishing was conducted at each site during a single pass each year to continue the protocol established with ISMP (USFWS 1987). Shoreline habitats were electrofished within each site. ~ Electrofishing efforts occurred prior to nets being set in late afternoon and subsequent to nets being pulled at night during each 18-hour sampling period. Electrofishing was conducted to monitor the fish community of Westwater Canyon and to target smaller Gila spp. in addition to the late 2